1. Field of the Invention
The present invention relates to a media drive system which has a plurality of queuing positions.
2. Background Art
In today's information-driven world, electronic media provides a mechanism for efficiently storing, and providing access to, large amounts of information. For example, large quantities of information can be stored on magnetic tapes, typically housed in a protective cartridge. Many such cartridges can be stored in magazines which can be remotely accessed by an automated robotic device, such as a “picker”, which can deliver the cartridges to a device, such as a computer tape drive. Many such magazines may be arranged to form a media library, which consists of hundreds, or perhaps thousands of tape cartridges, or other media objects.
As the size of media libraries increases, so too does the need to have efficient mechanisms for transporting the media between a media reader and the storage magazines. One such attempt to deal with this issue is described in U.S. Pat. No. 5,646,918 issued to Dimitri et al. on Jul. 8, 1997. Dimitri et al. describes the operation of a multi-gripper accessor in an automated storage system. While information from a first cartridge is being accessed in a drive unit, one of the grippers retrieves a second cartridge from a storage cell. When the drive unit is done accessing information from the first cartridge, the other gripper retrieves the first cartridge from the drive, while the first gripper delivers the second cartridge into the drive.
Increasingly, non-tape media are being used to store information. For example, optical disks provide high density storage, thereby providing a space savings over lower density media. In order to employ the use of existing storage libraries, including automated robotic devices, such as pickers, non-tape media may be housed within a cartridge having a tape form factor. In this way, an existing library may be converted to non-tape media with relative ease. In the case of media having a disk-like form factor—e.g., an optical disk—a single cartridge can contain multiple disks. This presents the problem of accessing the individual disks (or other removable media objects) from the storage cartridge once it has been placed in the drive unit by the picker. Moving the disks to and from the drive unit using a conventional loader adds an undesirable latency to the media loading/access process. When a disk is no longer needed, it must be removed from the drive unit and transferred back to the cartridge, where a new disk is accessed and transported to the drive unit. Therefore, it would be desirable to have a media drive system configured to reduce this type of loader function latency.